Earlier in the month, North Korea carried out its biggest ever sixth nuclear test, with seismic monitors measuring an "explosion" of 6.3 magnitudes near its main test site, sending tensions over its weapons ambitions to new heights.

On North Korean television, a newsreader called the test a "complete success" and said the "two-stage thermonuclear weapon" had "unprecedented" strength. Hours earlier, Pyongyang claimed its leader had inspected a hydrogen bomb meant for a new intercontinental ballistic missile.